In single-ended mode, VIN- is derived from the reference ladder.
Before enabling the comparator via the ENABLE register, the following registers must be configured for the single-ended mode:
The reference ladder uses the reference voltage (VREF) to derive two new voltage references, VUP and VDOWN. VUP and VDOWN are configured using THUP and THDOWN respectively in the TH register. VREF can be derived from any of the available reference sources, configured using the EXTREFSEL and REFSEL registers as illustrated in Comparator in single-ended mode . When AREF is selected in the REFSEL register, the EXTREFSEL register is used to select one of the AIN0-AIN7 analog input pins as reference input. The selected analog pins will be acquired by the comparator once it is enabled.
When the comparator core detects that VIN+ > VIN-, i.e. ABOVE as per the RESULT register, VIN- will switch to VDOWN. When VIN+ falls below VIN- again, VIN- will be switched back to VUP. By specifying VUP larger than VDOWN, a hysteresis can be generated as illustrated in Hysteresis example where VIN+ starts below VUP and Hysteresis example where VIN+ starts above VUP.
Writing to HYST has no effect in single-ended mode, and the content of this register is ignored.